It is a typical reaction of a caring family, friends or peers.
My best defense from the 'negative' comments is not notifying them in the first place. The only person I tell about my fasting are those who are supportive. To expect others who don’t believe in fasting to be supportive would be me forcing my beliefs on them.
If I am fasting and there is a function where food is presented I try to avoid those occasions or plan around them. But no one would ever be told about my fasting plans. I know most would see it as a taboo and I prefer not to deal with the negativity that comes from indifferences of beliefs.
Do you live with these people that are attempting to re-feed you? Maybe you can take a break from visiting them? If possible. For myself I find it almost impossible to fast while family is around.